Interplay of Three-Dimensional Morphologies and Photocarrier Dynamics of Polymer/TiO2 Bulk Heterojunction Solar Cells

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• 作者：Shao-Sian Li ; Ching-Pin Chang ; Chih-Cheng Lin ; Yun-Yue Lin ; Chia-Hao Chang ; Jer-Ren Yang ; Ming-Wen Chu ; Chun-Wei Chen
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：August 3, 2011
• 年：2011
• 卷：133
• 期：30
• 页码：11614-11620
• 全文大小：960K
• 年卷期：v.133,no.30(August 3, 2011)
• ISSN：1520-5126

文摘

In this study, we investigated the interplay of three-dimensional morphologies and the photocarrier dynamics of polymer/inorganic nanocrystal hybrid photoactive layers consisting of TiO₂ nanoparticles and nanorods. Electron tomography based on scanning transmission electron microscopy using high-angle annular dark-field imaging was performed to analyze the morphological organization of TiO₂ nanocrystals in poly(3-hexylthiophene) (P3HT) in optimal solar cell devices. The Three-dimensional (3D) morphologies of these hybrid films were correlated with the photocarrier dynamics of charge separation, transport, and recombination, which were comprehensively probed by various transient techniques. Visualization of these 3D bulk heterojunction morphologies clearly reveals that elongated and anisotropic TiO₂ nanorods in P3HT not only can significantly reduce the probability of the interparticle hopping transport of electrons by providing better connectivity with respect to the TiO₂ nanoparticles, but also tend to form a large-scale donor鈥揳cceptor phase-separated morphology, which was found to enhance hole transport. The results support the establishment of a favorable morphology for polymer/inorganic hybrid solar cells due to the presence of the dimensionality of TiO₂ nanocrystals as a result of more effective mobile carrier generation and more efficient and balanced transport of carriers.